Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K3/00—Materials not provided for elsewhere
  • C09K3/14—Anti-slip materials; Abrasives
  • C09K3/1409—Abrasive particles per se
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K3/00—Materials not provided for elsewhere
  • C09K3/14—Anti-slip materials; Abrasives
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B27/00—Other grinding machines or devices
  • B24B27/06—Grinders for cutting-off
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B28—WORKING CEMENT, CLAY, OR STONE
  • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
  • B28B5/00—Producing shaped articles from the material in moulds or on moulding surfaces, carried or formed by, in or on conveyors irrespective of the manner of shaping
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B28—WORKING CEMENT, CLAY, OR STONE
  • B28D—WORKING STONE OR STONE-LIKE MATERIALS
  • B28D5/00—Fine working of gems, jewels, crystals, e.g. of semiconductor material; apparatus or devices therefor
  • B28D5/0058—Accessories specially adapted for use with machines for fine working of gems, jewels, crystals, e.g. of semiconductor material
  • B28D5/007—Use, recovery or regeneration of abrasive mediums
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K3/00—Materials not provided for elsewhere
  • C09K3/14—Anti-slip materials; Abrasives
  • C09K3/1454—Abrasive powders, suspensions and pastes for polishing
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K3/00—Materials not provided for elsewhere
  • C09K3/14—Anti-slip materials; Abrasives
  • C09K3/1454—Abrasive powders, suspensions and pastes for polishing
  • C09K3/1463—Aqueous liquid suspensions
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
  • Y02P70/10—Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T83/00—Cutting
  • Y10T83/04—Processes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T83/00—Cutting
  • Y10T83/929—Tool or tool with support
  • Y10T83/9292—Wire tool

Definitions

• the present invention relates to a suspension of abrasive grains, in particular for machining silicon ingots, an abrasive tool, and in particular an abrasive wire, loaded with this suspension, and a method of sawing an ingot implementing such suspension or such abrasive tool.
• the manufacture of silicon wafers comprises a step of slicing silicon ingots.
• the silicon ingots are pushed against an abrasive wire rotating in a loop while recharging by passing through a suspension of abrasive grains.
• the silicon wafers can be intended for electronic applications or the manufacture of photovoltaic cells. Especially in this latter application there is a need to manufacture silicon wafers with a reduced thickness, of the order of 200 microns, in order to limit the amount of silicon needed to produce a watt.
• JP 10-180 608 recommends the use of abrasive grains in the form of platelets having a thickness at most equal to a quarter of their length and their width.
• JP 2003-041240 recommends a dispersion of grain sizes constricted around the median size. JP 2003-041240 also states that the aspect ratio average should be greater than or equal to 0.59. The grains disclosed in JP 2003-041240 would reduce the thickness variations along the manufactured slabs.
• An object of the invention is to at least partially solve one or more of the aforementioned problems, and in particular to improve the productivity of silicon wafer manufacturing processes.
• a suspension according to the invention is particularly effective for sawing ingots can explain theoretically, the inventors have discovered that the suspensions containing a high proportion of elongated grains among the large grain is advantageous and that, for these suspensions specifically, there is an optimum range for the mass content in grains. Surprisingly, they have demonstrated that this optimal range for the mass content is lower than that usually recommended is advantageous.
• a suspension according to the invention does not generate marks on the machined wafers (due to the friction of the abrasive tool) and allows a good renewal of the grains on this tool during its reloading.
• the abrasive grains When the median size D 50 of the set of abrasive grains is greater than 5 ⁇ m, or even greater than 6 ⁇ m and less than 9 ⁇ m, or even less than 8 ⁇ m, the abrasive grains preferably represent more than 30% and less than 46 ⁇ m. % of the mass of said suspension.
• the abrasive grains When the median size D 50 of the set of abrasive grains is greater than 8 ⁇ m, or even greater than 9 ⁇ m and less than 12 ⁇ m, or even less than 10 ⁇ m, the abrasive grains preferably represent more than 35% and less than 47%. % of the mass of said suspension.
• the abrasive grains When the median size D 50 of the set of abrasive grains is greater than 12 ⁇ m and less than 20 ⁇ m, or even less than 15 ⁇ m, the abrasive grains preferably represent more than 31% and less than 48% of the mass of said grit. suspension.
• the ratio of the volume percent S (D 40 -D 60 ) of grains having a circularity less than 0.85 in the particle size fraction D 40 -D 60 of said set of abrasive grains divided by the median size D 50 , or "ratio R 40-60 ", is greater than 1 and less than 5, preferably less than 3, or even less than 2.7, the circularity and the percentiles being as defined above.
• This ratio can be greater than 1.5, or even greater than 1.7.
• the set of abrasive grains is such that: 10 % ⁇ ⁇ 3 - 10 - 20 ⁇ 60 % and or 5 % ⁇ ⁇ 10 - 20 - 40 ⁇ 40 % , and or 20 % ⁇ ⁇ 20 - 40 - 60 ⁇ 50 % and or 0 % ⁇ ⁇ 40 - 60 - 80 ⁇ 20 % , and or 5 % ⁇ ⁇ 60 - 80 - 97 ⁇ 40 % , " ⁇ nmp " being the ratio (S (D n -D m ) -S (D m -D p )) / S (D m -D p ) in percentage, "S (D i -D j )" being the volume percentage of grains having a circularity of less than 0.85 in the particle size fraction D i -D j .
• ⁇ 40 - 60 - 80 ⁇ 70 % ; preferably 20 % ⁇ ⁇ 20 - 40 - 60 ⁇ 50 % , and 0 % ⁇ ⁇ 40 - 60 - 80 ⁇ 20 % , indeed ⁇ 40 - 60 - 80 ⁇ 7 % .
• ⁇ 3-10-20 may be greater than 20%, or even greater than 25% ⁇ 10-20-40 may be less than 35%, or even less than 30%, or less than 25%.
• ⁇ 20-40-60 may be greater than 15%, even greater than 25%, or greater than 35%.
• ⁇ 40-60-80 may be less than 15%, less than 10% or less than 7%, or even less than 5%.
• ⁇ 60-80-97 may be greater than 10%, or even greater than 15% or even greater than 20%,
• the median size D 50 is greater than 8 ⁇ m and the size fraction D 40 -D 60 comprises more than 15%, or more than 20%, as a percentage by volume, of grains having a circularity of less than 0. 85.
• the binder is preferably an organic binder.
• a suspension according to the invention has a viscosity of between 20 and 30 cPas, measured by Brookfield viscometer "DV-II + Pro", using the needle 63 and a rotational speed of 200 RPM (revolutions per minute).
• the invention also relates to a tool comprising abrasive grains fixed on a support or agglomerated to each other by means of a suspension according to the invention.
• the tool may in particular be a support wire coated with a suspension according to the invention, for example an abrasive wire for sawing ingots, and in particular silicon ingots.
• the invention also relates to a method of machining an ingot, and in particular to a method of sawing an ingot by means of a tool according to the invention, and in particular a wire abrasive according to the invention.
• the ingot may comprise more than 50%, more than 80%, more than 90%, more than 95%, more than 99%, more than 99.9% or even 100% of a constituent selected from a semiconductor material , in particular mono or polycrystalline silicon, an arsenide, in particular gallium arsenide (GaAs), indium phosphide (InP), a metal oxide, a ferrite.
• the method can be adapted to obtain, after sawing, a wafer having a thickness of less than 200 ⁇ m, less than 150 ⁇ m, and even less than or equal to 100 ⁇ m.
• the tool is reloaded by passing through a suspension according to the invention.
• the invention also relates to a wafer obtained according to a machining method according to the invention.
• the inventors have discovered that the mass content of abrasive grains in the suspension which is optimal for maximizing the sawing speed depends on the specific surface area of the powder, conventionally measured by BET. The greater the specific surface area, the higher the mass content must be.
• the suspension may in particular be a suspension according to the invention.
• a photograph of the suspension is taken and processed using a SYSMEX FPIA 3000 type device.
• Such a granulometric curve can be carried out using a laser granulometer.
• a SYSMEX FPIA 3000® device advantageously makes it possible to obtain such curves. In the examples below, the sizes were determined with such a device.
• the grain size (on the abscissa on the above-mentioned curve) corresponding to the percentage, by volume, of p % on the ordinate is conventionally referred to as "percentile” or “percentile” D p .
• percentile or "percentile” D p .
• 10% by volume of grains have a size greater than or equal to D 10 and 90% of the grains, by volume, have a size strictly less than D 10 .
• D p -D q denotes the particle size fraction comprising all the grains having a size greater than or equal to D q and less than or equal to D p .
• S (Dp-Dq) denotes the volume percentage of elongated grains in the particle size fraction D p -D q .
• ⁇ nmp denotes the ratio (S (D n -D m ) -S (D m -D p )) / S (D m -D p ) in percentage.
• ⁇ 3 10 20 (S (D 3 -D 10 ) -S (D 10 -D 20 )) / S (D 10 -D 20 ).
• ⁇ nmp therefore indicates the relative growth of the proportion of elongated grains of the particle size fraction D n -D m to the particle size fraction D m -D p .
• suspension denotes a liquid containing a powder that is substantially homogeneously dispersed, a suspension that may optionally contain a dispersing agent.
• FIG. 1 illustrates the method used to determine the circularity of the grains.
• steps of classification, sorting, for example by sieving, or mixing of different size fractions may be necessary in order to obtain elongated grain proportions corresponding to those of a set of grains of a suspension according to the invention.
• the objective is to manufacture solid bodies having sufficient strength to "burst" during grinding.
• the solid bodies prepared must not be simple agglomerations of grains that may crumble during grinding, such crumbling not making it possible to obtain sufficient elongated grains for industrial use. All synthetic processes are possible, simple tests to find the most favorable conditions.
• step b) optional, the solid bodies are reduced, for example crushed, so as to increase the amount of particles that can be selected in the optional step c).
• the optional step c) is intended to ensure that after bursting of the particles introduced into the mill, the grains obtained at the outlet of the mill will have sufficient sizes for the powder to remain relatively coarse.
• the minimum size of the solid bodies or particles entering the mill is at least two times greater than the maximum grain size of the powder to be manufactured.
• step d) use is made of a grinder favoring shear stresses, preferably a roller mill.
• Attrition mills are not considered suitable for efficiently producing a high quantity of elongated grains.
• the roll gap can be adjusted to change the particle size distribution and the proportion of the elongate grains.
• step e An additional step e), optional if the powder obtained at the end of step d) is satisfactory, can then be implemented in order to select the preferred particle size ranges.
• This step may comprise a classification, preferably by elutriation, i.e. by density separation by stirring in water. This technique is in fact well adapted to the fine granulometry of the grains.
• An optional step f) can also be implemented in order to eliminate by ironing the magnetic particles in particular introduced during step d).
• this step is performed using a high intensity deferrator.
• the quality of the powder obtained after grinding is verified, preferably by sampling, for example under a microscope, a scanning electron microscope or any known means for controlling the shape of the particles. grains.
• the abrasive grains are preferably of a material having a Vickers HV 0.5 microhardness greater than 7 GPa.
• the nature of the abrasive grains may be in particular that of abrasive grains used until now as polishing or sawing materials.
• the grains may be of a material selected from the group consisting of carbide silicon, cerium oxide, diamond, boron nitride, alumina, zirconia, silica and combinations of one or more of these materials.
• Such abrasive grains are commercially available.
• silicon carbide GC TM Green Silicon Carbide
• C TM Black Silicon Carbide
• SIKA TM manufactured by Saint-Gobain Materials in Lillesand, Norway.
• the alumina powders may be chosen for example from FO (Fujimi Optical Emery), A (Regular Fused Alumina), WA (White Fused Alumina) and PWA (Platelet Calcined Alumina) manufactured by FUJIMI Inc.
• Silicon carbide grains are particularly advantageous.
• the abrasive grains comprise more than 95%, or even more than 97.5% of silicon carbide, as a percentage by weight.
• the last 2.5% can be impurities.
• impurities means the inevitable constituents necessarily introduced with the raw materials during the manufacture of the grains.
• the compounds forming part of the group of oxides, nitrides, oxynitrides, carbides, oxycarbides, carbonitrides and metallic species of sodium and other alkalis, iron, vanadium and chromium are generally impurities.
• the silicon carbide grains preferably have a density greater than 3.0.
• the silicon carbide is crystallized in alpha form.
• the percentile D 20 is greater than 9 ⁇ m, greater than 11 ⁇ m, and / or less than 15 ⁇ m, less than 14 ⁇ m, or even less than 13 ⁇ m.
• the percentile D 40 may be greater than 5 ⁇ m, or even greater than 8 ⁇ m and / or be smaller than 20 ⁇ m, even less than 15 ⁇ m, or less than 10 ⁇ m.
• the median size D 50 may be less than 30 ⁇ m, less than 20 ⁇ m, less than 15 ⁇ m and / or greater than 1 ⁇ m, greater than 3 ⁇ m, greater than 5 ⁇ m, greater than 7 ⁇ m, or even greater than 9 ⁇ m.
• a suspension conventionally results from a mixture of a base powder in a liquid binder.
• the binder makes it possible to fix the abrasive grains on a support, and in particular on a support wire intended for sawing ingots, and in particular silicon ingots.
• This attachment may be rigid, or conversely, classically leave a possibility of grain mobility relative to each other.
• the binder is preferably an organic binder.
• the binder may comprise water, a base material and one or more additives.
• the quantity of water is preferably between 10 and 75% by weight relative to the mass of the suspension.
• the base material may be selected from alkali metal hydroxides, such as lithium hydroxide, sodium hydroxide and potassium hydroxide, alkaline earth hydroxides, such as magnesium hydroxide, sodium hydroxide, and the like. calcium hydroxide and barium hydroxide, and combinations of these different materials.
• the content of this base material is conventionally between 3.5% and 20% by weight relative to the total liquid mass of the suspension.
• At least one lubricant is generally used.
• a lubricant may be chosen especially from a polyethylene glycol, benzotriazol, oleic acid and mixtures thereof.
• a lubricant may be, for example, Rikamultinole manufactured by Rikashokai or Lunacoolant manufactured by Daichikagaku.
• the lubricant content is preferably between 0 and 50% by weight relative to the mass of the suspension.
• the binder may comprise a polymer or a copolymer formed of ethylene glycol monomers, preferably a polyethylene glycol.
• Other organic binders such as PVA or PMMA may be suitable since they can be in liquid form or in solution.
• the suspension can be manufactured simply by mixing the aforementioned raw materials.
• a method of manufacturing a suspension is described in particular in US 2006/0249134 .
• the suspension is conventionally arranged on a support wire having for example a thickness of between 100 and 200 ⁇ m.
• the support wire can in particular be made of hard steel or of an alloy such as a nickel-chromium alloy or an iron-nickel alloy or a metal having a high melting point such as tungsten or molybdenum, or be made of polyamide.
• an abrasive wire guided by rollers, turns in a loop while passing through a suspension to recharge in abrasive grains. It rubs on a sawing ingot, typically of the order of 200 mm in length and diameter, so as to cut a slice, or "slab", of this ingot.
• the ingot may in particular be a polycrystalline silicon ingot of purity greater than 99.99% by mass.
• the wafer is sawn to have a thickness less than 200 microns, less than 180 microns, less than 150 microns, less than 130 microns, less than 120 microns, even less than 100 ⁇ m.
• S% denotes the volume percentage of elongated grains in the different granulometric slices.
• N% denotes the percentage in number of elongated grains in the different granulometric slices.
• Table 1 Percentile ( ⁇ m) Example P1 P2 D 97 5.2 6.2 D 80 6.9 7.8 D 60 8.5 9.3 D 50 9.2 10 D 40 9.9 10.7 D 20 11.8 12.4 D 10 13.5 13.6 D 3 16.2 15.6 S% P1 P2 D 80 -D 97 18.6 8.6 D 60 -D 80 22.8 8.9 D 40 -D 60 23.7 9.6 D 20 -D 40 32.7 12.7 D 10 -D 20 38.5 15.1 D 3 -D 10 52.6 29.2
• Example Fraction D 50 ( ⁇ m) R S% / D 50
• R 40-60 S (D 40 -D 60 ) / D 50 P1
• the examples were made from different suspensions prepared from these powders, in a manner similar to that of the example described in JP 2003-041240 .
• the binder is polyethylene glycol, molecular weight 200 provided by VWR. Different amounts of powder have been added to the binder. Table 6 gives the mass content in grains of the various suspensions thus obtained, in percentage on the basis of the mass of the suspension. The suspensions were then used to saw a silicon ingot, following the protocol described in the example of JP 2003-041240 .
• the machining speed of the silicon ingot by the abrasive wire (which rubs on the ingot in a plane perpendicular to the direction of advancement of the silicon ingot), that is, the number of sawn ingots per unit time, was measured, each time under the same conditions.
• the speeds obtained with the various suspensions were compared with the speed obtained with the suspension of the example "Ref.2".
• the ratio between the speed obtained with a suspension and the speed obtained with the suspension of the example of "Ref.2”, called “G gain”, makes it possible in particular to measure the impact of the grain powder used ( P1 or P2) and the mass content in grains.
• a suspension according to the invention made from a powder of elongated grains of type P1 has better performance than a suspension manufactured from a powder P2.
• a suspension according to the invention thus allows a high sawing speed, that is to say a good productivity, but also the manufacture of slabs, in particular of silicon, of a very thin thickness, and in particular of less than 180 ⁇ m, even less than 150 microns, or even of the order of 100 microns, with a low rejection rate.
• the invention provides a particularly powerful suspension for cutting silicon wafers. With a suspension according to the invention, it is thus particularly possible to manufacture cells photovoltaic having a yield between the amount of electrical energy generated and the amount of silicon used particularly interesting.
• a suspension according to the invention could be used in other applications than abrasive wire. It could in particular be used to manufacture other sawing tools or, more generally, other machining tools.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Mechanical Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Ceramic Engineering (AREA)
• Mechanical Treatment Of Semiconductor (AREA)
• Polishing Bodies And Polishing Tools (AREA)
• Processing Of Stones Or Stones Resemblance Materials (AREA)

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• 2009
  • 2009-07-09 FR FR0954792A patent/FR2947831B1/fr not_active Expired - Fee Related
• 2010
  • 2010-07-09 CN CN201080031058.2A patent/CN102482554B/zh not_active Expired - Fee Related
  • 2010-07-09 US US13/382,677 patent/US20120132045A1/en not_active Abandoned
  • 2010-07-09 EP EP20100740358 patent/EP2451884B1/fr not_active Not-in-force
  • 2010-07-09 KR KR20127003393A patent/KR20120039006A/ko not_active Application Discontinuation
  • 2010-07-09 UA UAA201115468A patent/UA105529C2/ru unknown
  • 2010-07-09 SG SG2012000808A patent/SG177524A1/en unknown
  • 2010-07-09 JP JP2012519114A patent/JP2012533172A/ja active Pending
  • 2010-07-09 ES ES10740358T patent/ES2421751T3/es active Active
  • 2010-07-09 RU RU2011153091/04A patent/RU2529856C2/ru not_active IP Right Cessation
  • 2010-07-09 WO PCT/IB2010/053161 patent/WO2011004352A1/fr active Application Filing

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